1. Field of the Invention
The present invention relates to an improvement in a camera using a film with a magnetic storage portion.
2. Related Background Art
In a conventional film feeding apparatus of a camera, when the tip end portion (so-called leader portion) of a film is engaged with a sprocket or film take-up spool of a camera, the sprocket or film take-up spool is driven to load the film. With a film feeding apparatus of this type, however, a user must set the tip end of a film, resulting in cumbersome operations. If a user sets the tip end of a film at a wrong position, the film cannot be satisfactorily loaded. In addition, when a user carelessly pulls the tip end of a film, the film is unexpectedly exposed, and can no longer be used.
For this reason, the following film cartridge of a new type is proposed in U.S. Pat. No. 4,834,306.
The film cartridge comprises a film passage slit, a film one end of which is fixed to a feed spool, and which is wound around the feed spool, a pressing member which is arranged coaxially with the feed spool, and regulates the outermost circumferential portion of the film from extending radially so as to substantially prevent the outermost circumferential portion of the film from contacting the inner wall of the film cartridge, a release portion for continuously releasing the outermost circumferential portion of the film from radial regulation of the pressing member, and a guide portion for guiding a portion of the film released from regulation toward the film passage slit. The outermost circumferential portion of the film and the pressing member are set in a slide-free state by extension of the outermost circumferential portion by a loose winding state of the film caused by rotation of the feed spool in a film thrust direction of the film, and a driving force in the thrust direction is applied to the film, thus allowing the film to be thrusted from the film cartridge. In the following description, a film cartridge of this type which can exhaust a film upon rotation of a feed spool will be referred to as a thrust type film cartridge.
FIGS. 16 and 17 show the thrust type film cartridge. FIG. 16 is a longitudinal sectional view of the cartridge, and FIG. 17 is a cross-sectional view thereof.
In FIGS. 16 and 17, a thrust type cartridge 302 comprises a film 301, a film passage slit 303, a feed spool 304, a fixing portion 304a for fixing one end of the film 301, a pressing member 305, a regulating portion 305a, a release portion 306, and a guide portion 307.
When the thrust type film cartridge 302 is used, after the cartridge is loaded in a camera, the feed spool 304 of the cartridge 302 is rotated by a fork to exhaust the film 301. The film 301 is pushed out until it is wound around a film take-up spool of the camera. Thereafter, the film 301 is fed by the film take-up spool. With this arrangement, a user need not touch the tip end portion of the film 301, thus eliminating the conventional drawback.
Recently, U.S. Pat. No. 4,864,332 discloses a camera, which uses a film having a magnetic storage portion, and writes photographing information such as a shutter speed, an aperture value, a date, a title, and the like in the magnetic storage portion using a magnetic head, or reads out a film speed or the like, which has already been written in the magnetic storage portion.
In a camera of this type, in order to reliably write or read information in or from a film with a magnetic storage portion using a magnetic head, a structure for urging the magnetic storage portion against the magnetic head with a given pressure, so that the magnetic head can reliably contact the magnetic storage portion, is required. For this purpose, a film urging member such as a pad must be arranged at a position opposing the magnetic head to sandwich the film therebetween. Therefore, when the film with the magnetic storage portion is used in the thrust type film cartridge, the following problems are posed.
1) When a film urging member is urged beforehand against a magnetic head by an elastic member such as a spring, if a film thrust operation is performed at a high speed, a load generated when the tip end of a film is inserted into a gap between the magnetic head and the film urging member becomes a shock force, and the film may buckle or may be damaged.
2) When a film urging member or a magnetic head is movable by another motor in a direction of thickness of a film, and the film urging member or the magnetic head is escaped in the direction of thickness of the film until the tip end of the film passes the position of the magnetic head and the film urging member by a film thrust operation, a driving source such as the motor is required, resulting in high cost. A timing for urging the film against the magnetic head becomes complex, and as a result, an electrical circuit becomes complicated.
This problem is particularly serious when a motor drive unit is attached to a camera, and a film is fed at high speed by the motor drive unit in place of a film feed circuit incorporated in the camera.
Japanese Patent Application Laid-Open No. 55-22799 discloses a camera, which records, as magnetic information, information associated with a film on a member moved integrally with a film feed operation, and reads the information in the film feed operation.